The synthesis of new materials with potential as acidic catalysts or supports is of interest to industries that employ zeolites and clays in these traditional uses, e.g. the petrochemical industry. These minerals are crystalline, open-framework silicates that have pores and channels (in the case or three-dimensional zeolites) or galleries (two-dimensional clays and pillared clays) available as microenvironments for chemical reaction. The smectite clay minerals of interest in this invention have two tetrahedral silicate layers sandwiching a central octahedral layer in a so-called 2:1 arrangement, see FIG. 1. Isomorphous substitutions in the lattice such as Mg(II) for Al(III) in the octahedral layers of montmorillonite clays or Li(I) for Mg(II) in the octahedral layers of hectorite clays cause an overall negative charge that is compensated for by the presence of interlayer, or gallery cations. A significant amount of interlayer water is also present and the cations are easily exchangeable. The d(001) spacing indicated in FIG. 1 is the crystallographic unit cell dimension along the c-axis, and includes the fixed measurement of the clay layer (.about.9.6.ANG.) along with the variable interlayer or gallery spacing.
The usual method for modifying such silicate minerals is by ion-exchange, where the alkali or alkaline earth cation is replaced by, for example, a catalytically active species. However, a more direct method is to incorporate intercalants, especially more complex molecules, during hydrothermal crystallization of the silicate. The inventive technique is applicable to hectorite clays that were made in the presence of water-soluble porphyrins and metalloporphyrins, and is also applicable to a wide variety of organics and organometallics, of the types illustrated in FIG. 2.
Mn-porphyrins supported on clays have recently been demonstrated as promising hydrocarbon mono-oxygenation catalysts. The adsorption characteristics of dye-clay mineral systems have been extensively studied in terms of staining tests and metachromasy, which has implications in geochemistry and agriculture, and fluorescence to probe photoprocesses at solid surfaces and photo-redox reactions in organized media. The dyes methyl green (MG) and alcian blue (AB) are biological stains, and ethyl violet (EV) is known to display metachromasy with clays. The other intercalants or templates used are bulky transition metal complexes, such as Ru(II)o-phenanthroline) and Co(III)sepulchrate. Metal chelates such as Ru(II)- and Fe(III)-phenanthrolines adsorbed onto clays have been studied by electric dichroism, in terms of ligation, and are props of the gallery space as pillars. All synthesized materials were characterized by X-ray powder diffraction (XRD), microanalysis, Nz BET surface area measurements, thermal gravietric analysis, and diffuse reflectance UV-visible spectroscopy (DRS) when appropriate.